Dozens of aftershocks followed the quake, which hit on Thursday evening around 9:26 pm (1226 GMT), and officials warned the death toll could rise as rescuers scoured the collapsed buildings.

"I felt quite strong jolts, which I had never experienced before," Shunsuke Sakuragi, a prefectural official in the city of Kumamoto, told AFP. "People were shocked."

By Friday morning, the government said it had confirmed at least 761 people had been injured, at least 44 seriously. An official from the local Kumamoto disaster agency said at least nine were dead.

As the death toll rose through the night, an eight-month-old baby girl was pulled from the rubble alive and unharmed, public broadcaster NHK reported.

"As far as we can tell from infrared images from a police helicopter, there appears to be a significant number of houses destroyed or half-collapsed," said disaster minister Taro Kono.

"There are fears the number of injured could rise."

In the town of Mashiki, scores of people gathered in front the town hall following the powerful shaking, some in tears while others wrapped themselves in blankets to ward off the nighttime chill.

Nuclear plants in the region were unaffected, but several major manufacturers including Honda, Bridgestone, and Sony said they had suspended operations at factories in the area.

Train services on Kyushu were temporarily halted after Thursday's earthquake and a super fast bullet train derailed -- luckily while it was empty

-- said Yusuke Nanri, a spokesman for operator JR Kyushu.

Prime Minister Shinzo Abe pledged the government would do everything possible to support search-and-rescue work and help those who had fled their homes.

"We are doing everything to avoid a second disaster because of aftershocks, and to offer the necessary help to those affected," he told reporters Friday morning.

Some 1,600 military personnel were joined by nearly 2,000 police officers and more than 1,300 firefighters to help in the search and rescue efforts, government spokesman Yoshihide Suga said early Friday.

"I ask people in the disaster zone to act calmly and help each other," he said earlier.

The initial quake, which struck at a shallow depth of 10 kilometres (6.2

miles) was followed two and a half hours later by another one measuring 6.4 magnitude in the same region, according to the Japan Meteorological Agency. 

In total, more than 100 earthquakes rocked the region after the first hit, and officials warned the could continue for a week or so.

Abe convened a meeting of emergency management officials, while other senior officials also held a series of meetings to share information and to plan further rescue efforts, Suga said.

Japan's two sole operating nuclear reactors, located on Kyushu, were functioning normally, an official at the Sendai plant told AFP.

The meteorological agency said there was no danger of a tsunami after Thursday's quake, which the US Geological Survey measured as a 6.2 magnitude. 

Japan, one of the most seismically active countries in the world, has been particularly on edge over the vulnerability of nuclear power plants after a massive undersea quake on March 11, 2011, that sent a tsunami barrelling into the country's northeast coast.

Some 18,500 people were left dead or missing, and several nuclear reactors went into meltdown at the Fukushima plant in the worst atomic accident in a generation.

Japan sits at the junction of four tectonic plates and experiences around

20 percent of the world's most powerful earthquakes.

But rigid building codes and strict enforcement mean even powerful tremors frequently do only limited damage. (AFP)